RNA-polymerase binding sites within the tra region of the F factor of Escherichia coli K-12

Chimeric plasmids containing the tra operon of the Escherichia coli K-12 F factor were used to map by electron microscopy the RNA polymerase binding sites within the contiguous F EcoRI restriction fragments f6, f16, f1, f17, f19 and f2. These fragments have been previously cloned in the EcoRI site of pSC101 to give the chimeric plasmids pRS27 (f6, f15), pRS29 (f15, f1) and pRS31 (f17, f19 and f2)]. The results may reflect the presence of a number of previously unrecognized promoters within the traY----Z operon.